The Cartographers’ Guild is a forum created by and for map makers and aficionados, a place where every aspect of cartography can be admired, examined, learned, and discussed. Our membership consists of professional designers and artists, hobbyists, and amateurs—all are welcome to join and participate in the quest for cartographic skill and knowledge.

Although we specialize in maps of fictional realms, as commonly used in both novels and games (both tabletop and role-playing), many Guild members are also proficient in historical and contemporary maps. Likewise, we specialize in computer-assisted cartography (such as with GIMP, Adobe apps, Campaign Cartographer, Dundjinni, etc.), although many members here also have interest in maps drafted by hand.

If this is your first visit, be sure to check out the FAQ. You will have to register before you can post or view full size images in the forums.

Hybrid View

Image Resolution & Printing

I have a photograph I want to print and frame in my house, but when I first tried printing it, it came out a bit blurry. How do I fix that?

The original is 3011x2260 pixels and 72 pixels/inch. I initially took that to be printed on photo paper at Walgreens. I printed it out at 24' x 36'. It was a bit too fuzzy.

I have photoshop and my girlfriend found some other program she heard was good for resizing photographs, but we aren't confident what should be done. I can resize the picture, and change the pixels/inch in photoshop, but I don't know if it is doing any good.

3011x2260 px is the mount of information you have. 72 dpi is just a tag attached to the image suggesting how big it should be printed and is completely irrelevant.

Scaling up the image is just going to smear the image out which makes it blurry. The best you can do is adjust the kind of blur or other artifact you get from this process by using different resampling algorithms. The information about what the extra pixels "should" be simply isn't there.

To get a decent print, you're going to want at the absolute least 150 dpi, and more likely 300. Different kinds of image require different resolutions to look clear though. Text and sharp fine lines require higher resolution than photos. You aren't going to be able to achieve that with that image at that size. No software you throw at it is going to fix this, it can just produce the blur at an earlier step in the process. Your only options are to get a bigger original version of the image, if such a thing exists, to accept a smaller print, to accept the blur, or to give up.

Supposedly the most recent revision of Photoshop has a new upsampling algorithm that can enlarge images with less blurring than has ever been possible before. I have not had the opportunity to try it yet, but if you aren't using the most current CC version of Photoshop, you can get a 30-day trial and see how it does. I'll admit to being skeptical that it's as good as they claim.

Some of the non-linear filtering papers that have been coming out of Adobe the last few years suggest some excellent things either available or nearly so. Sometimes I wish I was 20 years younger, because folks just learning this stuff now will have a rather different set of primitives than the ones I tend to think in...

The quality of your resizing results will likely depend very much on the nature of your input and how far you want to enlarge it. Most modern enlargers do pretty well with images that have good edges and moderate internal texture on areas. It also helps if the image to be enlarged has never been heavily JPEG compressed., because JPEG compression can do some horrendous damage to photos, especially those with clean edges or blocks of low-contrast color.

I'll look into a trial for the new photoshop, thanks for the suggestion!

Also, how big of a factor does the paper or the printer have on the outcome? I got it printed at Walgreens on glossy photo paper. If I went to a different printer or had more premium paper would it make an appreciable difference in the crispness or blurriness of the print?

In my experience, most of the glossy printers that drugstores (and the Walmarts of the world) use for photos are 300dpi equivalent or greater. Until you get your source information to that resolution, you're unlikely to see much improvement by changing printing processes or papers. Different sized images can result in different printers being used, with different results (e.g. a 36" wide print is likely to come off the wide-format inkjet printer, while 3"x5" prints are likely to come off the dye sub photo printer - hardware and process varies widely, though).

As a digital printer, I prefer high resolution TIF, rather than JPG, but such files are massive in comparison. While some solutions are getting better, I've never found a consistently good quality image enlarger, not in 20+ years in the graphic arts industry.

It won't help your photo issue, but for mapping, the reason I use a vector application (Xara Photo & Graphic Designer 9) as opposed to an image editor (Photoshop, GIMP, etc) is that I create maps in units (usually inches) and not pixels. Pixels aren't even a consideration until I export the file, once I complete the map. While maintaining the same dimensions that I created the map, I am able to export to most graphic formats at any resolution I want and export an infinite number of versions in whatever resolution needed. And as far as what a vector map looks like, most people think I'm using Photoshop or GIMP and not a vector application at all.